A tandem type color laser printer including a plurality of photosensitive bodies, corresponding to toners of yellow, magenta, cyan and black respectively, parallelly arranged in a prescribed direction and a plurality of developer cartridges corresponding to the photosensitive bodies respectively for feeding the toners is known as a color printer of an electrophotographic system.
For example, a color laser printer including a drum unit integrally retaining a plurality of photosensitive drums corresponding to toners of respective colors, a plurality of developer cartridges including developing rollers and a pressing mechanism provided on a main body casing for pressing each developer cartridge is proposed as such a tandem type color laser printer.
In the color laser printer, each developer cartridge is detachably mounted on the drum unit so that the developing roller thereof is in contact with the corresponding photosensitive drum, and pressed by the pressing mechanism toward the corresponding photosensitive drum.